1. Field of the Invention
This invention relates to a mid-mount type lawn tractor having a vehicle body extending fore and aft in a traveling direction, a first wheel unit disposed adjacent one end in the fore and aft direction of the vehicle body, a second wheel unit disposed adjacent the other end in the fore and aft direction of the vehicle body, and a mower unit connected to the vehicle body between the first and second wheel units.
2. Description of Related Art
When grass twines around in the mower unit or when cutting blades become worn, the interior of the mower unit must be cleaned or the cutting blades ground or changed. Such an operation carried out while the mower unit remains connected to the vehicle body would encounter difficulties of access, i.e. difficulties in inserting hands and tools into the mower unit. Conventionally, therefore, a maintenance operation is performed after detaching the mower unit from the vehicle body. The interior of the mower unit has to be cleaned or components thereof changed frequently. It is a heavy burden on the operator to have to detach the mower unit from the vehicle body and connect it to the vehicle body again each time such an operation is carried out.
An object of this invention is to provide a lawn tractor with a relatively simple construction for facilitating an operation to maintain and inspect the interior of a mower unit without detaching the mower unit from a vehicle body.
The above object is fulfilled, according to this invention, by a mid-mount type lawn tractor comprising a vehicle body extending fore and aft with respect to a traveling direction, a first wheel unit disposed adjacent one end in a fore and aft direction of the vehicle body, a second wheel unit disposed adjacent the other end in the fore and aft direction of the vehicle body, a mower unit connected to the vehicle body between the first and second wheel units, a wheel support frame supporting the first wheel unit and pivotably connected to the vehicle body, wherein the first wheel unit is displaceable relative to the vehicle body with a pivotal movement of the wheel support frame relative to the vehicle body, to produce one of a device for swinging the wheel support frame to produce the running posture and the jack-up posture.
With this construction, when the jack device is operated to pivot the wheel support frame relative to the vehicle body, the wheel support frame produces the jack-up posture lifting one end of the vehicle body about the wheel axis of the second wheel unit, with the first wheel unit acting as a reaction point on the ground for lifting the vehicle body. As a result of the lift of the vehicle body, one of the mower unit in the fore and aft direction of the vehicle body is raised to expose the interior of the mower unit upward.
When an operation is carried out by accessing the interior of the mower unit, such as for cleaning the mower unit or changing cutting blades, the interior of the mower unit may be exposed upward toward the first wheel unit while the mower unit remains connected to the vehicle body. Thus, the operator may perform a maintenance operation efficiently by inserting the hands and tools therein with ease. Moreover, by using the wheel support frame as a lever for jack-up, the jack device may have a relatively small and simple construction only for turning the wheel support frame.
It is convenient where the first wheel unit is an idle wheel unit, and the second wheel unit is a drive wheel unit. This is because, where a construction where employed for jacking up the drive wheel unit, the transmission line to the drive wheel unit must be remodeled which would complicate the jack-up mechanism.
Taking balance in running and the like into account, the idle wheel unit preferably includes a pair of right and left idle wheels supported by right and left ends of the wheel support frame.
In a preferred embodiment of this invention, the wheel support frame is supported by the vehicle body to be pivotable about an axis extending in the fore and aft direction and disposed between a support point supporting one of the idle wheels and a support point supporting the other idle wheel, a distance from one of the support points to the axis being greater than a distance from the other support point to the axis. With this construction, the vehicle body may be lifted about a reaction point on the ground provided by the one of the idle wheels supported at the opposite ends of the wheel support frame, whose support point is at the greater distance to the axis of pivotal movement of the wheel support frame. Thus, the vehicle body may be jacked up high for the total length and pivoting stroke of the wheel support frame. As a result, one end of the vehicle body is lifted as high as possible, to expose the interior of the mower unit to a great extent to facilitate an operation for inspecting the interior or changing components.
In another embodiment of this invention, the idle wheels are caster type wheels each supported by the wheel support frame to be swivelable about a caster axis, and a lock device is provided for releasably locking the caster type wheel to a direction where a wheel axis of the caster type wheel is farther away than the caster axis from the axis about which the wheel support frame is pivotable relative to the vehicle body. With this construction, when lifting the vehicle body by the wheel support frame, the lock device is operated to keep at least one of the caster type wheels to a predetermined orientation. This maximizes the distance from the axis of pivotal movement of the wheel support frame to the reaction point on the ground. The vehicle body is lifted high for the total length and pivoting stroke of the wheel support frame. That is, the characteristics of the caster type wheel are used to lift the vehicle body as high as possible, to expose the interior of the mower unit to a great extent to facilitate an operation for inspecting the interior or changing components. This is achieved by a relatively simple construction additionally requiring the lock device only.
In a further embodiment of this invention, the mower unit is connected to the vehicle body through a pair of front and rear pivotal links vertically pivotably supported by the vehicle body, and a link lock device is provided for locking against downward pivotal movement one of the front and rear pivotal links close to the wheel support frame. With this construction, the vehicle body is jacked up with the link lock device operated to a locking state, and the pivotal link remote from the idle wheels disconnected from the mower unit. Alternatively, after the vehicle body is jacked up, the link lock device operated to the locking state, and the pivotal link remote from the idle wheels is disconnected from the mower unit. Then, with one end of the vehicle body in the jack-up posture, the mower unit is suspended from the vehicle body through only the one of the front and rear pivotal links closer to the idle wheels. Compared with the case of the mower unit remaining suspended through both the front and rear pivotal links, the mower unit may be suspended to form a large angle with the ground, thereby exposing the interior by an increased degree upward. Thus, the interior of the mower unit lifted by the jack-up of the vehicle body has a large upturned angle for the height to which the vehicle body is lifted. Without lifting the vehicle body to a great height, the interior of the mower unit may easily be turned by an increased degree upward for allowing an operation to be carried out for the interior easily and efficiently.
In a further embodiment of this invention, the jack device is connected to the wheel support frame or the vehicle body through a play-accommodating device for allowing the wheel support frame to roll about the axis relative to the vehicle body. With the lawn tractor which employs this construction, when the wheels ride on a ridge or sink in a recess, the wheel support frame rolls about the axis relative to the vehicle body to vary the height of the right and left wheels relative to the vehicle body. Consequently, the transverse posture of the vehicle body is maintained horizontal or near horizontal, whereby no or little variation occurs in the height above the ground of the left side and right side of the mower unit. Even where the ground is rugged, the rolling of the wheel support frame maintains the left side and right side of the mower unit at a substantially constant height above the ground. An operation is carried out with a substantially uniform right and left cutting height to produce an excellent result.
Moreover, the above feature is provided by a simple construction additionally requiring the play-accommodating device only, which is achieved by utilizing, for the rolling mechanism, the wheel support frame pivotable relative to the vehicle body to lift the latter. Such a construction has an advantage in terms of cost also.
In a further embodiment of this invention, the jack device is a manually operable screw type jack device. A simplified jack-up structure is realized by employing the screw type jack device.
The lawn tractor according to this invention may have an engine disposed rearwardly of a wheel axis of the second wheel unit. Then, the weight of the engine assists in lifting the wheel support frame. Other features and advantages of this invention will be apparent from the following description of the embodiments to be taken with reference to the drawings.